


Ultimatum

by Very_Niche_Interests



Category: Shall We Date?: Obey Me!
Genre: Ambiguous Genitals, Anal, Anal Sex, Anal Virgin, Blackmail, Breeding, Captive, Chains, Claiming, Coercion, Dirty Talk, Dom Leviathan, Eggpreg, F/M, GN Reader, Grand Admiral Leviathan, Jealousy, Light BDSM, M/M, Mildly Dubious Consent, Military, Military Kink, Military Uniforms, Navy, Objectification, Obsessive Behavior, Other, Oviposition, Ownership, POV Second Person, Possessive Behavior, Possessive Sex, Power Dynamics, Power Imbalance, Probably a little OOC but let a man dream, Reader-Insert, Unhealthy Relationships, forked tongue
Language: English
Status: Completed
Published: 2020-12-15
Updated: 2020-12-15
Packaged: 2021-03-09 22:46:41
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,024
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27984042
Author URL: https://archiveofourown.org/users/Very_Niche_Interests/pseuds/Very_Niche_Interests
Summary: You are caught stowing away aboard a Hell's Royal Navy ship. Unfortunately(?), none other than the Grand Admiral is on the ship as well, and he will be deciding your fate. He will forgive your crime—for a price. And you're more than willing to pay.
Relationships: Leviathan (Shall We Date?: Obey Me!)/Reader
Comments: 22
Kudos: 268





	Ultimatum

**Author's Note:**

> I uh. Based this on some Leviathan-themed "me time" I had.  
> Very much inspired by [fishheadakira's](https://fishheadakira.tumblr.com/post/627325133909049344/leviathan-grand-admiral-of-the-hells) art:  
>   
> I need more Grand Admiral Leviathan content, even if I have to make it myself ;w;

“Let me _GO_!” You shouted and struggled against the Demons gripping you tightly.

“Quiet!” One of them hissed and kicked at your ankles, causing you to stumble. Their grips tightened as they practically dragged you down the ship’s narrow hallway.

You continued to struggle, but it was futile. Internally, you cursed yourself for being so stupid. The coast had looked so clear from where you hid among various crates, but one soldier seemed to come out of nowhere. And that had been it; you were caught and now dragged to the captain probably.

The demons held you in front of a surprisingly ornate door, then knocked. “Sir! We have a stowaway.”

Some light shuffling some from behind the door, followed by a voice. “Bring them in.” Confident, commanding, and yet somehow familiar…

The moment the door opened your eyes went wide with recognition. This was no mere captain they had brought you to. The Demons that dragged you in pushed you to your knees so you had to look up at him.

Looming over you was none other than Leviathan. Grand Admiral of Hell’s Navy. You had seen him around town and RAD before. Shared some classes. Always shy, avoiding everyone, and usually wrapped in some fandom thing or another. The man standing before you looked so completely different from the man you knew. Like a different person altogether. His eyes stared down at you with a cold, calculating gaze—not a hint of his usual awkwardness even breached them.

“Fuck.”

“Dismissed.” Levi waved his hand at the Demons. Then they started to take you with them, he spoke again. “No. Leave them.”

They exchanged confused looks. Neither one of these low ranking Demons wanted to question the Grand Admiral, but one of them spoke up anyway. “Yes Sir. Will you need one of us to stay and take the prisoner to the brig when you are finished?” It was the most diplomatic way to get the question across without seeming insubordinate.

A small smirk tilted Levi’s lips. “No. They will remain with me until we get to port. I have a… _special_ treatment for stowaways found aboard my ship.” His voice was cold and menacing, far from the stammering mumble you were used to.

This change in demeanor sent shivers up your spine. An unmistakable heat began to pool between your legs as your body reacted to his dominance. You had always found Leviathan attractive—not that he would have ever given you the time of day. A Demon Lord who hated “normies” was unobtainable to you, even as shy as he seemed. This new side of him only drew you to him more.

“Dismissed.”

“Sir!” The Demons saluted and exited the Admiral’s Quarters, shutting the door behind them as they did.

The moment they were gone, Levi returned his attention to you. He began circling you slowly and locked the door when he came behind you.

You did your best to keep eye contact with him. Those commanding eyes…

When he returned to your front, he knelt. A single gloved finger tilted your head up. “… You’re a lucky one.” He mused. “If you had been found by anyone other than the new recruits, you’d likely be eaten.” His hand cupped your chin roughly; you couldn’t look away from him now even if you wanted to. “And normally _I_ would have already eaten you by now. Do you know why I haven’t?”

You tried to shake your head, but his grip was too tight. “No.” Your answer was curt.

Levi glared at you, tightening his grip further. “This isn’t RAD. You will address me with the respect I am owed here.”

“No, _Sir_.”

Satisfied, he released your face. “That’s better.” He leaned in a little closer and took a deep breath. “Mmm… unless I am very much mistaken, I can _smell_ your arousal.”

The blush on your face drained completely. _Shit_.

“Seems I was right.” Levi smirked. “Since you appear to be interested, I will let you in on a little secret.” He ran a finger down your middle. “It’s my laying week. And I need an incubator if I am to produce spawn this season.”

Those words returned the blush to your face. Leviathan, like many other Sea Demons, would lay eggs in a host; that host would then give birth to monstrous creatures of the deep. It was usually some unwitting human: someone drawn from shore or saved from a shipwreck, or even one looking to gain power in exchange.

Never in an eon would you have guessed you would be approached by anyone to host—much less by _the_ Leviathan himself. How many times had you fantasized about it…? About a shy, nervous, nerdy Demon walking up to you and asking that you “help” him through a laying? But _this_... You gulped, trying to wet your dry throat. Every inch of you tingled with desire. 

Levi watched you intently, as if trying to follow your train of thought. “If you let me have my way with you,” He said, giving his ultimatum, “Then your stowaway transgression will be forgotten. You will be dropped off at the next port. I will ensure my subordinates do not make a mention of you. I won’t even inform Lord Diavolo.”

“… And if I don’t?” The question was more formality than anything. You had every intention of letting him take you right there. But you didn’t want to seem too eager. Plus, part of you wanted to know the stakes—it might make things even hotter.

“Then I will treat you like any other stowaway.”

So eaten. _Very_ high stakes, then. It wasn’t really a choice—and if you weren’t already willing to consent right away, that would have been a problem. Maybe it still was, but the lust swirling in your brain fogged your judgement.

Levi stood up, pulling you to your feet with him. “Well?” He questioned. “What’s your response? Will you host for me?”

“Yes!” You whined, needy and soaking. Seeing the look on his face, you quickly corrected yourself. “Y-Yes _Sir_!”

With a grunt of approval, Levi picked you up and hoisted you over his shoulder. It was like you weighed nothing to him, the ease with which he lifted you. You didn’t even bother struggling as he carried you through another door in his room.

The new room was dark—just barely illuminated by the soft glow of aquarium lights. There were hardly any decorations. A few beanbag chairs, some posters, shelves with a few scattered manga, and… _chains_. Long, sturdy chains were welded to the far iron wall.

Without warning, Levi shoved you against the opposite wall, not even setting you down. He smirked broadly, a strange glint shimmered in his eyes. Slowly, he leaned in and kissed you heatedly. In contrast, his hands moved quickly. He bound your wrists above your head in the chains, then ran his fingers down your entire body.

“Mmn!” You moaned into his kiss. The chains kept you from returning his touch. Oh how you longed to touch him, see if maybe you could fluster him. Draw out the bashful man you were used to—see just how long this military persona could last against his usual self.

He pulled away from you, staring at into your eyes intently. It was dark, but you could swear there was a blush on his face. A hesitation before he grabbed your clothes and ripped them off you. Part of him still registered that he was acting differently. But that part was small, and got drowned out by his mounting need to lay inside you. And the power he felt from his position of command only amplified his desires.

“Tell me you want it.” He said and unzipped his pants. “You are going beg for this. Thank me for giving you this privilege.”

You shuddered against the cold iron on your bare skin. “I want your eggs, Sir!” The whimper in your voice was pathetic. “Let me be your incubator~!”

With a growl, Levi’s wriggling cock squelched with slick. Unusual, even for a Demon’s genitals. It was large, dexterous, and would be ovipositing inside you soon. Not soon enough. “You really are a lucky slut.” He grunted, not even taking off the rest of his uniform before pressing back up against you.

The sensation of well-maintained fabric and regalia pressing against your skin made you moan for him. “Admiral…” You let out in a small pant. It didn’t feel right to call him Levi. Levi was the shut-in otaku. The man who crashed his lips against your feverishly was Grand Admiral Leviathan, and you had every intention of addressing him as such.

Thankfully, your use of his title seemed to rile him up more. “That’s right, slut, you don’t have the right to use my name.” He growled directly in your ear, making you shudder once again. “Call me anything else and you _will_ regret it.”

He didn’t need to tell you twice.

Slowly, his kisses moved to your neck and shoulders. He wanted to hear you moan. His hands reached behind you and grabbed at your ass. He fondled the mounds roughly in his palms, squeezing tight with his fingers.

“Ah!” You moaned and rolled your hips up against his. The cock slithered between your legs. It was less of a penis and more of a tentacle-like appendage of its own.

It slid up against your sex teasingly, leaving trails of thick lubricant in its wake. Oh how you wanted to have pleasure for yourself. To have him use his ovipositor to get you off… but those dreams were dashed. The appendage moved away as quickly as it had come.

You let out a small whine of protest, but gasped when you realized its next destination. Your ass. Stretching impossibly long, it slunk between your thighs and teased at your hole. Levi’s hands kept your cheeks spread to give it better access.

“P-Please… be gentle…” You had no idea if your begging would even matter to him. “I beg of you Admiral! I’ve never…. N-Nothing like this inside my ass before…”

His eyebrows raised as he looked at you. “Nothing this big?”

“Nothing _at all_ …” You admitted, the blush on your face practically glowing red from this point. You’d had sex, of course. But never had you done anal. The very thought of Leviathan popping your cherry, so to speak, made you grind up against him again. Your sex desperately wanted pleasure.

“At all…?” He parroted, moving his head back just a bit. He wanted to take in the look on your face. Make sure you weren’t lying. The way you gasped and squirmed whenever his cock prodded at your entrance told him you were being truthful. A wicked smile spread across his face; a dangerous glint in his eyes reflected in the dim lighting.

For once, he could have something no one else did. Something he didn’t have to be jealous about. Didn’t have to share. He was the first being to claim your ass. You couldn’t compare your experiences if this was the only one you had.

Fire burned throughout his whole body at that realization. With a low growl, he leaned in and kissed you passionately again. His tongue invaded your mouth with minimal resistance. The forked tips could just barely reach the back of your throat, eliciting a gagged moan from you.

Roughly, he moved one hand from your ass and hooked it under one of your thighs. With a single tug, he hoisted that leg over his shoulder to give himself more room to work.

“Fuck!” you whimpered at being positioned so awkwardly. Standing on the tip-toes of a single foot, hands affixed to the wall above you, and one leg stretched haphazardly against Leviathan. Internally, you thanked whatever powers that be for your dexterity.

“I’m going to be gentle,” he breathed, “but only because I don’t want to risk any damage to the incubation chamber.”

Well, that was certainly an epithet for the ass you’d not heard. But hearing it from Levi’s lips… It sent shockwaves up your spine. Right now, your body was nothing but a thing for him to use— _you_ were nothing but a thing for him to use. Just the host for his egg. An object. Incubator.

True to his word, Levi was gentle. His appendage slowly worked around your hole and coated the entire entrance with his warm lubricant. He huffed as he worked, eager to feel the friction of your walls around him. But he kept his ministrations slow. Methodical.

“Admiral!” You let out a delicious whimper when the tip began working its way inside. The tight ring of muscle tensed and shuddered around him, reluctant to allow anything inside.

Levi crooked his head to kiss and nibble down your throat. He kept one hand on your ass cheek, keeping it spread while your leg took care of the other side. That left his free hand to explore your body. As his fingers ran over your collarbone, a flash of anger struck him. Others had probably seen you like this. Others had probably kissed you, touched you, too. You’d only said your ass hadn’t been used. No mentions of other sexual encounters.

Forgetting his promise to be gentle, he rocked his hips forward and slammed himself inside you.

“FUCK!” You shouted, tensing at the pain.

He kept still, only feeling a little sorry for what he’d done. But the sound you made had been so worth it. The tremble in your voice, the high pitch, the way you keened into him after… No one had experienced that before. Just him. It calmed his jealousy enough for him to continue more tenderly.

Panting, you leaned your head back to press against the wall. It hurt so much. You weren’t expecting the sudden thrust. But mercifully he didn’t continue with the rough pace. Just staying inside you as his cock oozed generous amounts of lube inside you. The foreign feeling of it made you shudder. Your arms tugged fruitlessly against their restraints. You wanted to touch yourself. Look him in the eyes and masturbate as he fucked you full of his egg. “Please…”

Levi finished yet another dark hickey before looking up at your pathetic face. The soft flush, little tears… all of it drove him wild. “What are you begging for?” His cock pushed deeper inside you, drawing out another moan.

“I-I… I want… fuck please I need… for my…” You rolled your hips against him, hoping that your body could convey what your brain seemed incapable of doing.

Were he not in such a heightened state of arousal, Levi probably wouldn’t have known. Or would have pretended he didn’t know. “Oh? Are you really getting off to being used like this?”

You whimpered in response, but that wasn’t good enough.

His free hand tugged at your hair. “Say it.”

“Nnnng! Yes, Sir!!! Having you inside me is turning me on so much! Just the thought of carrying your egg is so hot!” You whined, still rolling your hips against him. “Please, I wanna cum to being used by you, Admiral…!”

“Hmph. And people think _I’m_ weird and perverted.” He taunted, letting his hand reach down to cup your sex.

“Thank you thank you thank you!!!” His fingers curled in just the right way to finally give you the pleasure you had been desperate for. The way his palm rubbed against you, it was like the pain from your ass disappeared.

With your mind focused on how good you felt, Levi let his wriggling appendage worm its way deeper inside you. He made sure to slick the area ahead with as much of his fluid as he could.

Pure pleasure. That’s all you could feel right now. Leviathan, stimulating you at both ends, had your brain dizzy. You moaned incoherently. “Admiraaaaah! Fuck! Nng… so gooood… oh yes yes yes!!!” The kisses and bites he left along your neck, shoulders, and jaw compounded into something beyond bliss. Everything inside you was screaming to cum. But you held yourself back. You wanted to finish with him. Only cum once he had finished his laying and your ass was full with his egg.

Agonizingly slowly, Leviathan’s appendage began to expand inside you. It worked you open tiny bit at a time. Wider than you had ever been or ever thought you could be. The little thrusting motions inside you helped coax your muscles to cooperate.

All the while, you writhed and moaned against the wall. Shamelessly loud. Shamelessly grinding into his hand for even more pleasure. “Admiral! Oh fuck, _fuck_!”

Suddenly Levi let out a gasp and moaned. He rutted his cock into you further. “Shit…” He growled. A little prematurely, his egg had dropped. He could tell your ass was only just barely ready. Enough so that it wouldn’t be dangerous to you or his egg, but still not to where a beginner could take it comfortably.

Not that either of you cared.

“Fuck…! Ohh fuck! _Finally_!” He moaned directly into your ear as his egg slowly made its way through the appendage to where it met your opening.

It started prodding into you slowly, straining the stretch of your muscles. It hurt, and you wanted to beg for it to go slower. But there was no stopping it.

Pulsating his member a few times, the egg finally popped passed the resistant ring of muscle. It was much smoother sailing as it glided up further into you.

“It’s so big…” You whimpered, already feeling heavy and full. “I wanna cum so badly!!!”

“Unf… Fuck! Fine. When you cum, you better scream my name so loud that you’ll be heard in the Celestial Realm.” He growled, his hand working harder and faster at your sensitive sex. “You’re **_mine_**. Only mine.”

“Yes! Yes yes I’ll do whatever you say just please give me your egg and let me cum!”

He was more than willing to oblige. With a loud moan and another huge spurt of his slick, the egg was finally free from his appendage and rested solely in you. All the while his hand continued to bring you to your own orgasm.

“ ** _LEVIATHAN_**!!!!” You screamed at the top of your lungs—so loud that your throat would likely hurt for it later. But you didn’t care. The orgasm wracking through your body drowned out any other thought or feeling. You barely even registered that your orgasm was spilling all over his hand and uniform.

It took several long minutes for the both of you to come down from your highs. Your body still trembled with aftershocks, even once the ovipositor slid back out of you.

Reluctantly, Levi eased you down to the floor. The restraints were removed as he did. He haphazardly moved some of his cushions and blankets to you so you wouldn’t be too uncomfortable.

You smiled up at him, looking fucked out and utterly blissful. No one had ever looked at him like that before. Who else had seen your face like this…? His aura flared in frustration. But you just laid down and rested, unflustered by his rage.

He stared at you in silence for a while, just watching you lay there. Whether you were sleeping or just relaxing, he didn’t care. You let him have his way with you. Held up your end of the bargain. But something stirred inside him.

A pit in his stomach churned. His part of the bargain had been to let you go free at the next port. Never speak of you again. Never to see you again, except to retrieve his hatched spawn. Demon though he was, he never went back on his word. He wasn’t _Mammon_ after all.

And yet… If you left, someone else might get to see you like this. Cover his marks with new ones of their own. Fuck out any memory of him from your ass. They’d hear your moans and see the way your face flushed and contorted in pleasure.

The mere thought of anyone else having you infuriated him. No. He couldn’t let that happen. You were going to stay with him. Be his. Only he would ever get to see you like this again. And you seemed so receptive to him… Him! It was a miracle. He couldn’t just let you slip out of his life.

He’d made up his mind.

It was only then he realized what a mess you’d made of his uniform. With a grunt of frustration, he cleaned off what he could and changed into fresh garments where he needed.

Dressed properly again, he returned to looking at you. It was obvious you were asleep now. Tired, probably, and letting your energy go to keeping his egg warm.

A dark gleam shone in his eyes. “You’re mine…” He knelt beside you, gingerly playing with your hair. “Mine. My incubator. My lover. No one else gets to have you ever again.”

You stirred a little under his touch, but remained peacefully unconscious.

Without really thinking, Leviathan grabbed more restraints and bound you to the chains once more. Only this time giving you enough slack to lay down, walk around, do whatever you wanted—except leave.

Plans formulated in his mind about how he was going to keep you. Here it would be as easy as this. He could tell his subordinates that he’d eaten you, make sure they knew the protocol for the next time a stowaway was found. Then only he would know the truth. Keep you a secret.

The House of Lamentation would be harder. Lucifer would surely skin him alive if he found Levi imprisoning a captive without his knowledge. And Lucifer would never let him keep a captive if he knew. But he could think of something. He had to. Wherever he lived, he needed you with him. Needed to see your face, the almost loving way you looked at him… And he could hear your moans whenever he wanted and know that he would be the only one.

It was worth the risk.

Sleepily, you opened your eyes and looked up at him. The feeling of new restraints confused you. “Um… what’s all this…? Don’t trust me not to cause trouble until we get to port.”

A blush crept across his face. Most of his bravado had been drained out of him with the orgasm. “No. I…. You’re not leaving at port. You’re mine.” He whispered. “You’re going to stay with me. Be my incubator forever. I can’t let anyone else have you now.”

You knew that you shouldn’t be okay with that. He wasn’t giving you a choice; he was telling you how things were going to be. But you would have agreed to it if he did, so did it really matter? “I’m yours. Grand Admiral, I am yours…”

Unable to hold himself back, he placed a hurried kiss on your lips. His anxious demeanor was beginning to show through. “G-Good.” He said, standing. He turned to leave, but hesitated and looked back at you. Naked, covered in blankets and pillows.

It was still cold. Tenderly, he took off the cape of his uniform and wrapped it around you. Since your clothes had been all but destroyed, it seemed like the right thing to do; plus he intended on keeping you naked for him. Then he could look at the marks he left on your body whenever he wanted…

“Thank you.” You hummed, curling into the cloak adorably as you lay back down. With a yawn, you fell back asleep.

“T-Too cute…” Levi stammered, exiting the room with a bright blush. He hurried to sit down at his desk and tried to get back to the paperwork he had been doing before you were brought to him. But he couldn’t concentrate.

You flooded his mind almost obsessively. Images of you round with his egg, dressed up in various cosplays for him to fuck you in, between his legs sucking him off while he gamed all flashed in his mind.

Leviathan was glad you stowed away on his ship.

**Author's Note:**

> Please do not put objects in your ass that don't have flared bases. Especially not smallish, rounded objects like silicone egg toys.
> 
> I'm still not sure how or if I'm going to write more, BUT I did do an [experimental drabble](https://archiveofourown.org/works/28115973/chapters/69923949) if you wanna read that!


End file.
